WRI - Global Power Plant Database | https://datasets.wri.org/dataset/globalpowerplantdatabase
This week’s assignment will encompass the following concepts covered in Class 3 lecture & lab:
Cartographic principles
Reference Maps vs Thematic Maps
Nominal vs continuous data types
Thematic strategies (3): Dot Density, Categorical Symbolization & Proportional Symbolization
QGIS style layers
Map layout elements: scale bars, map insets, complex legends & labels
This week’s reading will solely from Essentials of Geographic Information Systems textbook.
The Class 2 quiz (02/14/2022) will features 10 questions covering content in the textbook.
Readings outline (Chapter 3 + 4, with noted exceptions below):
Class 1 and 2 assignments featured the production of two maps - a small scale simple populated places global map and a large scale NYC 311 public service map. In a way, both maps are reference maps and simple thematic maps: they both have a theme but their primary purpose is simply to show the location of each theme:
The Class 3 mapping assignment will build on the first two maps, but with significantly more emphasis on the thematic dimension of the mapped data - the distribution of global power generation across both type (nominal) and generation capacity in megawatts (quantitative). This week’s mapping will also focus on map layout adding in both a scale bar and an inset map element.
The dataset utilized in this mapping will be the Global Power Plant Database v1.3.0 which is open and accessible at WRI.
Global Power Plant Database v1.3.0
This dataset format is .csv with lat/lon coordinates; we will rely on Class 2 fundamentals to import and initially map this dataset. A polygon reference layer will be added - countries, states or regions - and proportional as well as categorical symbolization will be developed for the power plants. Finally, map layout elements - particularly a simple scale bar and inset map - will round out the assignment deliverable.
A synopsis of the assignment steps:
Note general concepts covered in lecture and lab:
Subselecting features
Symbolizing nominal data
Proportional symbolization of continuous quantitative data
Scale bar production
Map inset production
Spatial bookmarks
Labeling in QGIS (lab)
Style layers in QGIS (lab)
Dot density mapping (lab)
.zip). Navigate QGIS to an Assignment.3 folder that you create; place and unzip the data folder and created a new .qgs assignment 3 project - all within the Assignment.3 directory. In the assignment data folder, find the following data sources:Assignment Data Directory
global.regions = world boundary polygon featuring UN world regions schemane_10m_admin_0_countries_lakes = Natural Earth world countries polygon featureUS_States = US states boundaries clipped to shoreline polygon featureglobalpowerplantdatabasev120 = WRI Global Power Plant DatabaseNote: as of June 2021, the WRI Global Power Plant Database has been updated and can be accessed HERE. Replace the
globalpowerplantdatabasev120in the assignment folder with this updatedglobal_power_plant_database_v_1_3.
.csv for the power plants. These features are located in the respective folders outside globalpowerplantdatabasev120:Assignment Data Directory
The three polygon features represent different recognized geographies at different scales. First, the UN regions schema is the smallest of the 3 scales; Natural Earth countries the second smallest; and US States represents the largest scale geography. You will pick one of these geographies that interests you most. For instance, the following 3 declarative sentences offer 3 example scale options to use for assignment 3:
Polygon Features for 3 scales that can be utilized in Assignment 3
right-click feature layer > Properties > Labels > Single Label
Single Label Tool Dialog
Labels Result
right-click > Open Attribute Table:
Open Attribute Table
> Select by Expression:
SQL Tool Button
*>Fields and Values > NAME:
SQL Expression Setup - Search
Note: keep in mind that the exact SQL expression that you use for your own query will be structured differently.
SQL Expression Setup
Select Features based on SQL Expression
Selected Results will be Highlighted on Map
.shp into the assignment data folder:Export a Selection
.qgs project. The first will be large scale, centered on Ukraine; and a second will be a regional scale and position to capture the geographic context of Ukraine relative to its postion within the European continent:View > New Spatial Bookmark:
Spatial Bookmark Setup
View > Show Spatial Bookmarks:
Spatial Bookmark Access
Spatial Bookmark Access
.csv for the power plant locations:Delimited Text Selector
Select by Location
Select by Location
power.plants.ukraine.shp:Export Selected Features
Unlike assignments for class 1 and class 2 that stopped short of any thematic symbolization (resulting in a map similar to above - simple, one symbol points atop polygons), this assignment pushes further into the data attributes themselves to provide the map user with much more information beyond location alone. Here two thematic symbolizations will be provided. The first will be the size of the plant based on megawatt capacity (MW); and secondarily, the type of the plant based on primary fuel. This provides the user with 3 dimensions of data for the plants:
capacity_mw)primary_fuel)Utilize the steps below with the following video guide (click on image for video in new window) to develop the map symbolization:
right-click > Properties > Symbology (Simple Marker) > Size > Assistant (via dropdown):
Size Assistant
Size Assistant Parameters
Note: experiment with all the option parameters to become familiar with this powerful tool. Also note that the default style in the current LTR is a nested proportional symbol.
Proportional Symbols on Map
right-click > Properties > Symbology > Categorized (top bar):
Populate the tool:
Value: primary_fuel
Symbol: simple circle
Color Ramp: Random colors
click Classify (lower left)
- In conjunction with the Size Assistant, activate Data-defined Size Legend, also covered in the video.
right-click > Properties > Symbology. Notice the Advanced tab, lower-right. Activate Data-defined Size Legend:
Data-defined Selector
Note: the Collapsed Legend option is very elegant and effective over the default Separate legend items.
Collapsed Legend
As the proportional symbolization of larger points may cluster and crowd out smaller point quantities, apply approximately 60% transparency to the primary layers, also covered in the video.
Properties > Symbology > click-on Symbol > decrease Opacity to approximately 50-60%:
Apply Transparency
Make sure to save the .qgs early in the visualization process before proceeding to the final layout.
Quantitative Proportionality + Categorized Symbology
With initial symbolization complete, create a new layout (Layout Toolbar > New Layout) and draw out a map instance. All preparation and layout components are covered in video guide.
Proportional & Categorical Symbolization:
To development the final map design, utilize the diagram, map example PDFs and the video guides in the Video Guides section below.
Final map layout will include the following elements on either a 11x17" or 8.5x11" Landscape 300 DPI:
Note: if a PDF export is exhibiting a large file size,
.pngor.tiffare acceptable.
Assignment 3 Deliverable Example
.png or .tiff - both are acceptable to the Canvas submission endpoint for this week’s submission:Export as Image Option
Compressed, Nested Proportion Legend Style
Map Canvas vs. Map Layout Stroke Weights